1. Field of the Invention
The present invention relates to a work holding device that holds a work that is to be processed by a processing tool and a cutting device including such a work holding device.
2. Description of the Related Art
Conventionally, a cutting device that performs a cutting process on a work based on predetermined data by use of numerical value control performed by a microcomputer or the like is known. Such a cutting device includes a work holding device that holds the work. Such a cutting device and such a work holding device are disclosed in, for example, European Patent No. 2247405.
FIG. 7 is a perspective view of a conventional cutting device 300. The cutting device 300 includes a carriage 312 movable in an X-axis direction, a table 322 movable in a Y-axis direction, and a main shaft 314 movable in a Z-axis direction. A processing tool 332 is attached to the main shaft 314.
A work holding device 310 is located on the table 322. As shown in FIG. 8, the work holding device 310 includes a frame 328 that holds a discus-shaped work 200 (shown in FIG. 7) and a frame 326 that supports the frame 328. The frame 326 is rotatable about a center axis O1 that is parallel or substantially parallel to the X-axis. The frame 328 is rotatable about a center axis O2 that is parallel or substantially parallel to the Y-axis.
As shown in FIG. 9A and FIG. 9B, the frame 328 includes a base member 150 and a cap member 152. A thread 150a is formed in an outer circumferential surface of the base member 150, and a thread 152a engageable with the thread 150a is formed in an inner circumferential surface of the cap member 152. The cap member 152 is detachable from the base member 150.
The work 200 is caused to be held by the frame 328 as follows. The cap member 152 is detached from the base member 150 and is put outside the cutting device 300. Next, the work 200 is placed on the base member 150. Then, the cap member 152 is attached to the base member 150 and is rotated. As a result, the work member 200 is sandwiched between the cap member 152 and the base member 150 and thus is held by the frame 328.
The work 200 which has been processed is recovered from the frame 328 as follows. The cap member 152 is detached from the base member 150 and is put outside the cutting device 300. Next, the work 200 is removed from the base member 150.
As described above, with the work holding device 310, the cap member 152 needs to be put outside the cutting device 300 in order to cause the work 200 to be held by the frame 328 and also to be recovered from the frame 328. This involves an undesirable possibility that the cap member 152 is lost during the operation.
The frame 328 is located inwardly relative to the frame 326, which is substantially rectangular. When rotating the cap member 152, an operator's finger is likely to contact the frame 326. Because of this, the operation of detaching the cap member 152 from the base member 150 and the operation of attaching the cap member 152 to the base member 150 are difficult.